Track mounting and tensioning assembly for tracked vehicles

ABSTRACT

A track mounting and tensioning assembly for track-type tractors and other tracked vehicles includes an endless sprocket-driven track, and a walking beam-bogey wheel assembly engaging the track. The walking beam-bogey wheel assembly is supported on a vertical lever pivotally connected intermediate its ends to the frame of the vehicle. The lower end of the lever is pivotally connected to an intermediate point on the walking beam. The upper end of the lever is pivotally connected to power means such as a fluid operated cylinder which applies pressure to the lever in the direction of track tensioning. The bogey wheels themselves thus become the tensioning instrumentalities which maintain the track under constant tension despite track length changes which normally occur during operation of tracked vehicles over rough terrain.

United States Patent 1191 Schoonover 11 3,744,857 [451 July 10, 1973TRACK MOUNTING AND TENSIONING ASSEMBLY FOR TRACKED VEHICLES [5 6] 9References Cited UNITED STATES PATENTS 3,182,741 5/1965 Roach 180/953,447,620 6/ 1969 SChOOIlOVGl 1 80/9.64 X 2,284,821 6/1942 $351M 305/31X 3 ,446,302 5/ 1969 SChOOllOVCl 305/ 10 X 3,343,832 9/1967 Gustafssonm,305/27 Primary Examiner-Richard J. Johnson Attorney-Christensen & Sanbom[5 7 ABSTRACT A track mounting and tensioning assembly for tracktypetractors and other tracked vehicles includes an endless sprocket-driventrack, and a walking beambogey wheel assembly engaging the track. Thewalking beam-bogey wheel assembly is supported on a vertical leverpivotally connected intermediate its ends to the frame of the vehicle.The lower end of the lever is pivotally connected to an intermediatepoint on the walking beam. The upper end of the lever is pivotallyconnected to power means such as a fluid operated cylinder which appliespressure to the lever in the direction of track tensioning. The bogeywheels themselves thus become the tensioning instrumentalities whichmaintain the track under constant tension despite track length changeswhich normally occur during operation of tracked vehicles over roughterrain.

11 Claims, 7 Drawing Figures PAIENTEmuumen 3.744.857

Richard H14. Schoon over INVEN'TOR 20 I8 HHy.

PAIENIwJuL 1 01915 3. 744. 857

Fig. 5.

Richard H. H. Schoonover INVENTOR BY TRACK MOUNTING AND TENSIONINGASSEMBLY FOR TRACKED VEHICLES This invention relates to track mountingand tensioning assemblies for tracked vehicles.

As is well known, the tracks of a track-laying vehicle lengthen andshorten with bogey wheel position changes during operation of thevehicle over rough terrain. This decreases the track drive efficiency,increases wear on component parts and may even loosen the tracksufficiently to cause its demounting from the drive sprockets andbogeys.

vThe problem customarily is overcome by the application of spring loadedtrack tensioners mounted within the track assembly itself.

Serious problems attend the operation of track tensioners of theforegoing class. Since they are located inside the track assembly, thespring components load with mud, bolt threads rust and mud plugs theentire system. Debris, mud and snow build up on top of the tensioningassembly, adding weight to the vehicle, freezing up and breaking loosein chunks. Upon passing the sprockets and bogeys, the chunks put excesstension on the tracks, and even may arrest the motion of the vehicle orcause the loss of a track.

In addition, the conventional tensioning devices do not providesufficient travel to make possible easy re moval of track sprockets orbogeys; are difficult of access; and are difficult to remove and/orassemble. Still further, the manner of application of the spring loadedtensioners is such that when the vehicle is thrown into reverse, thetensioning effect of the spring is cancelled, loosening the track.

It is the general purpose of the present invention to provide a trackmounting and tensioning assembly for tracked vehicles which overcomesthe foregoing problems by applying uniform and optimum tension to thetracks of tracked vehicles under all conditions of operation; whichtensions the track whether the vehicle is progressing forwardly or inreverse; which is located out of the mud and water in which the vehicleoperates and hence is not susceptible to becoming clogged; which may beadjusted to apply fixed or variable tension as described; which iseasily assembled and installed; which provides sufficient travel fortensioning under extreme conditions as well as for track removal; andwhich is applicable to tracked vehicles of various classes, includingarticulated four-tracked vehicles having limited space for mounting thetensioning assembly.

The manner in which the foregoing and other objects of this inventionare accomplished will be apparent from the accompanying specificationand claims considered together with the drawings, wherein:

FIG. 1 is a fragmentary view in side elevation of a tracked vehicleincluding the herein described track mounting and tensioning assembly;

FIG. 2 is a fragmentary view in plan of the vehicle;

FIG. 3 is a fragmentary view in front elevation looking in the directionof the arrows 3-3 of FIG. 1;

FIG. 4 is a fragmentary plan view of the herein described track mountingand tensioning assembly in an alternate embodiment;

FIG. 5 is a fragmentary view in side elevation of the embodiment of FIG.4;

FIG. 6 is a detail transverse sectional view taken along line 6-6 ofFIG. 5; and

FIG. 7 is a detail view of an alternate tensioning element.

In its broad concept, the presently described track mounting andtensioning assembly for tracked vehicles comprises a sprocket-mountedendless track in combination with a walking beam-bogey wheel assemblyengaging the track.

a lever is pivotally connected intermediate its ends to the vehicleframe, adjacent the track. The lower end of the lever is pivotallyconnected to and supports the walking beam assembly at a pointintermediate the ends of the latter. Power means, for example, anhydraulic cylinder operated with hydraulic fluid under predeterminedpressure is mounted on the vehicle and engages the upper end of thelever for applying pressure thereto. This pressure is transmittedthrough the lever to the bogey wheels, the position of which thereuponshifts with lengthening and shortening of the track as required tomaintain the track under proper tension for optimum operation of thevehicle.

Considering the foregoing in greater detail and with particularreference to the drawings:

The tracked vehicle, the hull or frame of which is indicated at 10, isdriven by cooperating, endless belted track assemblies, one suitabletype of which is indicated generally at 12. Each assembly is of thedouble belt type driven by a pair of laterally spaced sprockets l4 fixedto a drive shaft 16. The shaft extends laterally outwardly from the hullof the vehicle and is connected to the vehicle motor.

Endless track 12 includes a pair of endless belts 18 which areinterconnected by a plurality of grousers 20. These comprise bar typemembers which span the distance between the two belts and are bolted orotherwise secured thereto along the lengths of the track at spacedintervals.

The ends of the grousers are provided with longitudinally extendingteeth or lugs 22. These mesh with sprockets 14 of the drive.

Wheel guides 24 extend inwardly from the central part of grousers 20.They receive and guide the support wheels (bogey wheels) with which theassembly is provided.

The bogey wheels are mounted on the walking beam assembly, indicatedgenerally at 26. The assembly may be of conventional construction andincludes a walking beam 28 which supports at each of its ends a shaft 30on which rotatably is mounted a bogey wheel 32.

Walking beam 28 is pivotally mounted intermediate its ends on shaft 34journaled in a bearing 36 and se cured in position by means of a washerand nut 38.

The bogey wheel assembly supports and guides track 12 in the usualmanner. In accordance with the present invention, however, it serves theadditional function of tensioning the track. This is accomplished bymounting the walking beam assembly on tensioning means which adjust todifferences in track length, thus applying tensioning pressure againstthe track.

In the FIGS. l3 embodiment of the invention, this result is accomplishedby providing a vertically arranged lever 40 formed in two segments.These may be formed integrally, as by forging or casting, or as twointerconnected parts.

The upper segment 42 comprises a flat plate which lies alongside frame10. The lower segment 44 comprises an angular extension projectingdownwardly and outwardly from the upper segment. The lower segmentmounts at its lower end a bearing 46 which receives shaft 34 of thewalking beam assembly.

Lever 40 is connected intermediate its ends to the frame of the vehicle.This is accomplished by providing a shaft 48 projecting laterallyoutwardly from the frame. The shaft is journaled in a bearing 50supported by lever 40. A nut 52 maintains the lever demountably on theshaft.

Power means are connected to the upper end of lever 40 for applyingpressure against the same and hence against the walking beam assembly. Aspring loaded cylinder, an air cylinder, an hydraulic cylinder or ascrew are examples of instrumentalities which may be employed for thispurpose.

In the illustrated form of the invention, a single acting hydrauliccylinder 56 is mounted with its case pivoted to a fixed bracket 58 andits piston rod pivotally connected to the upper end of lever 40 by meansof a pin 60. The single conduit 62 communicating with the cylinderbehind the piston then may be connected to a source of hydralic fluidunder pressure, as to the pump supplying hydraulic fluid to the steeringcircuit of the vehicle. The fluid pressure supplied to the cylinder isat a level predetermined to advance the piston of the cylinder whenpiston advancement is required to take up slack in the track, but topermit retraction of the piston when piston retraction is required toaccommodate shortening of the track under the influence of outsideforces.

Cylinder 56 thus applies resilient pressure continu ously to the walkingbeam assembly. Means also are provided, however, for placing the walkingbeam assembly under a fixed tension. The means employed for this purposeis shown particularly in FIG. 1.

A plurality of radially spaced sockets 64 are provided in the side wallof frame adjacent lever 40. These are disposed in an arc conforming tothe radius of lever 42. A bolt or pin 66 is removably mounted in anopening through the upper segment 42 of the lever arm. This openingregisters successively with various of sockets 64 as the lever sweepsthrough its arc. Accordingly the desired tension may be applied bycylinder 56 and lever 40 locked in a corresponding tension-applyingposition by inserting pin 66 in the particular one of sockets 64 withwhich it registers at the time.

When lever 40 is locked in this manner in a position of fixed tension,cylinder 56 may be entirely demounted and applied to secondary uses,such as providing a portable jack whenever there is need for such animplement in connection with the assembly, repair or operation of thevehicle.

It is to be noted particularly that the tensioning unit is mounted wellabove the tracks of the vehicle where it is free from fouling by mud,debris and water. Such fouling may be minimized even further byemploying the embodiment of the tensioning unit illustrated in FIGS.4-6, inclusive.

The tensioning unit of the latter figures is mounted within the hull ofthe vehicle where it is completely protected.

This result is made possible by the employment of a lever 70 provided inthree segments: an upper segment 72, a lower segment 74 and aninterconnecting shaft 76.

Upper lever segment 72 comprises a flat bar of heavy constructioncalculated to withstand the thrust applied to it. Additional thrustsupport may be included as required.

The upper end of lever segment 72 is pivoted to cylinder 56 by pivot pin60. The lower end of lever segment 72 is welded to the inner end ofhorizontal shaft 76.

The upper end of lever segment 74 is welded to the outer end ofhorizontal shaft 76. Its lower end mounts a bearing 78 in which isjournaled shaft 36 which mounts the walking beam assembly.

Horizontal shaft 76 is joumaled in a composite bearing assembly, theconstruction of which is particularly evident in FIG. 5.

The floor of hull 10 is cut away to provide an opening across which isbolted a bearing support 80. The latter supports centrally on its uppersurface an arcuate bearing part 82. A cooperating yoke-shaped bearingpart 84 also is fixed to and supported by support 80. Bearing parts 82,84 journal horizontal shaft 76 which interconnects the two leversegments.

The upper surface of bearing part 84 is provided with a transverse slot86. This receives upper lever segment 72 and permits its free angularmovement. Such movement is thus transmitted to horizontal shaft 76 andthence to lower lever segment 74 which supports the walking beamassembly.

Where a fixed adjustment, or a fixed adjustment coupled with a resilientadjustment, is desired, the embodiment of FIG. 7 may be employed. Inthis form of the invention, a screw 92, with or without an associatedspring 90, replaces cylinder 56 of the embodiment previously described.In the event of the omission of spring 90, the resiliency of thepneumatic tires of bogey wheels 32 supplies the cushioning action whichotherwise would be supplied by the spring.

With either of the forms of the apparatus above described, the objectsof the present invention abundantly are achieved. Fixed or runningtension is applied to the track as required to maintain it in optimumworking tension under all conditions of operation. The tensioningapparatus is protected, out of the way and does not become fouled withmud, water and debris, even under extreme conditions. The need for aseparate tensioning wheel is eliminated since the bogev wheels whichmount the track serve the supplemental functions of tensioning wheels.

Sufficient travel is provided to accommodate extremes of track lengthchange and make possible easy removal and mounting of the tracks fromand on the sprockets. Tension is applied even when the vehicle is throwninto full reverse.

These desired end results are obtained, furthermore, through the agencyof a relatively simple tensioning unit easily installed and serviced,and applicable to all of the usual categories of tracked vehicles.

Having thus described my invention, 1 claim:

I. A track mounting and tensioning assembly for a tracked vehicle havinga frame comprising:

a. an endless track trained about a drive sprocket mounted on saidvehicle frame b. a walking beam assembly having bogey wheels mountedthereon engaging the track,

c. lever means,

(I. first connecting means pivotally connecting a first portion of thelever means to the frame,

e. second connecting means pivotally connecting a second portion of thelever means to the walking beam assembly, and

f. power means engaging the lever means at a point spaced from the firstportion for applying a force thereto and hence to the walking beamassembly in the direction away from the drive sprocket to tension thetrack.

2. The track mounting and tensioning assembly of claim 1 wherein thelever means comprises an arm mounted vertically alongside the vehicleframe, an extension extending outwardly and downwardly from the arm, andbearing means mounted on the lower end of the extension and journalingthe second connecting means.

3. The track mounting and tensioning assembly of claim 1 including pinand socket means arranged for releasably interengaging the lever meansand vehicle frame in a predetermined position of adjustment of the levermeans for applying fixed tension to the track.

4. The track mounting and tensioning assembly of claim 1 wherein thepower means comprises a fluid operated cylinder.

5. The track mounting and tensioning assembly of claim 1 wherein thepower means comprises an hydraulic cylinder.

- 6. The track mounting and tensioning assembly of claim 1 wherein thepower means comprises a spring pressed hydraulic cylinder.

7. The track mounting and tensioning assembly of claim 1 wherein thepower means comprises screw means.

8. The track mounting and tensioning assembly of claim 1 wherein thepower means comprises spring pressed screw means.

9. A track mounting and tensioning assembly for tracked vehiclescomprising:

a. an endless track trained about a drive sprocket mounted on saidvehicle frame,

b. a walking beam-bogey wheel assembly engaging the track,

c. substantially vertically arranged lever means,

d. first connecting means pivotally connecting the lever means to theframe of the vehicle intermediate the lever means ends,

e. second connecting means pivotally connecting the lower end of thelever means to the walking beam intermediate the walking beam ends, and

f. resilient power means mounted on the vehicle and engaging the upperend of the lever means for applying resilient pressure thereto and henceto the walking beam-bogey wheel assembly in the direction away from thedrive sprocket to tension the track.

10. The track mounting and tensioning assembly of claim 9 wherein thelever means comprises a horizontal shaft extending laterally from withinthe frame to the exterior, an upwardly extending lever segment connected to the inner end of the shaft, a downwardly extending leversegment connected to the outer end of the shaft, coupling means couplingthe resilient power means to the upper end of the first lever segmentand the second connecting means to the lower end of the second leversegment, and pivotal mounting means pivotally mounting the horizontalshaft on the vehicle frame.

11. The track mounting and tensioning assembly of claim 10 wherein thepivotal mounting means comprises an arcuate bearing part underluing theshaft and a slotted bearing part overlying the shaft and securing meanssecuring both plates to the vehicle frame, the

, upper lever segment penetrating the slot in the retaining plate topennit its angular movement.

C-m0 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3744 57 Dated July 10, 1973 Richard H. A. Schoonover Inventor(s) It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

$- Column 4, Line 59, after "frame" insert 1 Column 5, Line 34, after"vehicles" insert --having a frame--.

- Signediand sealed this 8th. day of January 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. I RENE D. TEGTMEYER' Attesting Officer ActingCommissioner of Patents

1. A track mounting and tensioning assembly for a tracked vehicle havinga frame comprising: a. an endless track trained about a drive sprocketmounted on said vehicle frame b. a walking beam assembly having bogeywheels mounted thereon engaging the track, c. lever means, d. firstconnecting means pivotally connecting a first portion of the lever meansto the frame, e. second connecting means pivotally connecting a secondportion of the lever means to the walking beam assembly, and f. powermeans engaging the lever means at a point spaced from the first portionfor applying a force thereto and hence to the walking beam assembly inthe direction away from the drive sprocket to tension the track.
 2. Thetrack mounting and tensioning assembly of claim 1 wherein the levermeans comprises an arm mounted vertically alongside the vehicle frame,an extension extending outwardly and downwardly from the arm, andbearing means mounted on the lower end of the extension and journalingthe second connecting means.
 3. The track mounting and tensioningassembly of claim 1 including pin and socket means arranged forreleasably interengaging the lever means and vehicle frame in apredetermined position of adjustment of the lever means for applyingfixed tension to the track.
 4. The track mounting and tensioningassembly of claim 1 wherein the power means comprises a fluid operatedcylinder.
 5. The track mounting and tensioning assembly of claim 1wherein the power means comprises an hydraulic cylinder.
 6. The trackmounting and tensioning assembly of claim 1 wherein the power meanscomprises a spring pressed hydraulic cylinder.
 7. The track mounting andtensioning assembly of claim 1 wherein the power means comprises screwmeans.
 8. The track mounting and tensioning assembly of claim 1 whereinthe power means comprises spring pressed screw means.
 9. A trackmounting and tensioning assembly for tracked vehicles comprising: a. anendless Track trained about a drive sprocket mounted on said vehicleframe, b. a walking beam-bogey wheel assembly engaging the track, c.substantially vertically arranged lever means, d. first connecting meanspivotally connecting the lever means to the frame of the vehicleintermediate the lever means ends, e. second connecting means pivotallyconnecting the lower end of the lever means to the walking beamintermediate the walking beam ends, and f. resilient power means mountedon the vehicle and engaging the upper end of the lever means forapplying resilient pressure thereto and hence to the walking beam-bogeywheel assembly in the direction away from the drive sprocket to tensionthe track.
 10. The track mounting and tensioning assembly of claim 9wherein the lever means comprises a horizontal shaft extending laterallyfrom within the frame to the exterior, an upwardly extending leversegment connected to the inner end of the shaft, a downwardly extendinglever segment connected to the outer end of the shaft, coupling meanscoupling the resilient power means to the upper end of the first leversegment and the second connecting means to the lower end of the secondlever segment, and pivotal mounting means pivotally mounting thehorizontal shaft on the vehicle frame.
 11. The track mounting andtensioning assembly of claim 10 wherein the pivotal mounting meanscomprises an arcuate bearing part underluing the shaft and a slottedbearing part overlying the shaft and securing means securing both platesto the vehicle frame, the upper lever segment penetrating the slot inthe retaining plate to permit its angular movement.